U.S. Pat. No. 5,629,254 at column 29, line 5, et. seq., describes compounds of the Formula Ia: in which Ra may be a 1 to 20 carbon atom hydrocarbon group, (Rb) may be a 6 to 16 carbon atom aryl group, M may be titanium, zirconium or hafnium. X1 and X2 may be a halogen atom and Y1 may be a divalent-silicon containing group.
There may also be used the transition metal compounds obtained by substituting titanium metal of hafnium metal . . . for zirconium metal in the above-exemplified compounds. [Col. 32, 11. 5-9]
It appears that the sole reference to a method which may be useful for preparing the Formula Ia compounds is found at column 13, lines 21-25 of U.S. Pat. No. 5,629,254 which states:
The transition metal compounds according to the present invention can be prepared in accordance with the methods described in Journal of Organometallic Chem. 288 (1985), pages 63 to 67, European Patent Publication No. 0,320,762 specification and Examples thereof . . . .
Neither reference specifically exemplifies the synthesis of any titanocene. Nor does any working example of U.S. Pat. No. 5,629,254 do so.